if you stick to the rules you should have no problems..
1 bosch pump/injector best pump.
2 properly filtered oil if you do it youself you know what you are putting into your tank you monitor the quality if you use incorrect filtered oil your asking for trouble.
3 correct switch over temp, if you switch over at a too low temp you get lumpy running. (there are ways around this)
i think times have changed now the kits you can buy are very complex processor controlled monitoring temps.
filtering of the oil is very important but simple, its done progresivly 600 then 100 50 10 then to 1 micron.
there are a lot of people out there using this system with no problems, its very big in france and germany people
doing big milage no problems
A Mercedes 300TD has done 58,374 miles on veg oil!
A Mercedes benz 250 TD has done 62,100 miles on veg oil!
A VW Bus T2/3 has done 93,150 miles on veg oil!
A Ford Fiesta has done 66,500 miles on veg oil!
A Opel Corsa B Combo has done 76,500 miles on veg oil!
A AUDI AUDI -TDI has done 80,000 miles on veg oil!
A VW Golf III has done 65,205 miles on veg oil!
A Opel Astra 1.7D has done 60,237 miles on veg oil!
A VW Golf SDI has done 65,000 miles on veg oil!
A Opel Astra 1.9 TD has done 70,000 miles on veg oil!
A Isuzu trooper (jackaroo in australia) four wheel drive has done 51,000 miles on veg oil!
A vauxhall 1.7td van astra has done 75,000 miles on veg oil!
A Hino FB14 has done 78,000 miles on veg oil!
A Citroen ZX Citroen ZX aura has done 120,000 miles on veg oil!
A toyota 1hz has done 75,000 miles on veg oil!
A fiat ulysse has done 256,000 miles on veg oil!